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Biomedical subjects

G Finet

Publications and source records attributed to G Finet.

At least 19 recordsLinked to original sources
PubMed2006

[Myocardial bridging and coronary spasm on effort].

The discovery of myocardial bridging during coronary angiographies is common. Yet these bridges are rarely the origin of acute coronary syndrome. We report the case of an active 45 year old man with no cardiovascular risk factors who had acute coronary syndrome. Emergency coronary angiography just revealed two myocardial bridges on the anterior interventricular artery which did not explain this acute episode. A subsequent second angiogram together with endocoronary echography demonstrated that there was no atheroma and a methergin test set off diffuse coronary spasm. The association of myocardial bridging and coronary spasm has only rarely been reported in the literature. We describe the clinical, therapeutic and prognostic characteristics.

Angina, Unstable↗
PubMed2005

[Morphological and functional characteristics of the culprit coronary artery in acute coronary syndrome].

In the catheter laboratory, faced with a patient with unstable angina, the problem is not the diagnosis of epicardial coronary artery stenosis but rather the atherothrombotic complexity of the stenosis and the identification of other less stenotic lesions on angiographically normal or nearly normal segments. The authors describe two appearances with morphological analysis of the vulnerable or unstable plaque and functional analysis of coronary artery vasomotricity. Acute coronary syndromes due to a clearly stenotic atherothrombotic plaque on angiography pose no diagnostic problems. However, an acute coronary syndrome may be more difficult to assess when angiography shows only simple irregularities of the lumen or no lesions at all. In these cases, angiography is said to be normal and the coronary arteries are considered to be possibly "healthy". Evaluation of the vessels' vasomotricity is especially valuable in this context. Using pharmacological stress tests, endovascular ultrasonography is a complementary diagnostic tool which allows identification of the unstable atheromatous process or of a partial atherothrombosis masked by positive remodelling process. These tests may also indicate the optimal treatment.

Angina, Unstable↗
PubMed2004

Influence of the morphogranulometry and hydrophobicity of talc on its antisticking power in the production of tablets.

Antisticking power varies according to the talc considered. It is difficult to define the physical properties of talc implicated in its antisticking power. In this work, different talcs were characterized and an evaluation made of their performance in reducing sticking in tablet manufacturing. Determination of the specific surface area was made by permeametry, morphogranulometric analysis by laser diffractometry using a method, which made it possible to assess the mean thickness of talc particles, and measurement of water absorption kinetics was taken to assess hydrophobicity. The relationship between the characteristics of talcs and their antisticking power was then considered. There is a correlation between the particle size of talc and surface hydrophobicity. The detaching force of tablets appears to be dependent on the basal dimension of talc.

Hydrophobic and Hydrophilic Interactions↗
PubMed2004

Experimental assessment of new stent technologies: validation of a comparative paired rabbit iliac artery study model.

Preventing coronary in-stent restenosis is a major challenge for physicians and industry. To assess new stent technologies, a comparative paired iliac artery model in rabbits is proposed. One tubular stent was implanted in each external iliac artery in 12 rabbits (i.e., 24 stents). An artery overdilatation level of 20% was strictly observed. Restenosis was examined at 30 days by angiography, intravascular ultrasound (IVUS) examination, and histomorphometry. On quantitative angiography, the mean loss of angiographic diameter was 9.8 +/- 4.4% in the right as compared to 9.3 +/- 55% in the left artery (p = 0.75). On IVUS, the volume of intrastent neointimal proliferation was 26.6 +/- 4.9 mm(3) in the right and 25.8 +/- 3.5 mm(3) in the left artery (p = 0.58). In histomorphometry, the neointimal proliferation area was 0.78 +/- 17 mm(2) in the right and 0.76 +/- 0.17 mm(2) in the left artery (p = 0.87). Intrastent neointimal proliferation was comparable between the left and right arteries of all rabbits. The model has three main advantages: (1) arterial dilatation and thus arterial wall aggression are controlled, (2) pairing makes each animal its own control subject, and (3) the statistical power for comparative testing is maximized. The model enables the effect of a new drug-delivery device to be assessed.

Animals↗
PubMed2004

Preconditioning during coronary angioplasty: no influence of collateral perfusion or the size of the area at risk.

AIMS: It is unclear whether the protection observed in human heart following repetition of brief episodes of ischaemia is due to opening of coronary collaterals or to ischaemic preconditioning. We investigated whether the improvement in ST segment change following repeated episodes of brief ischaemia during coronary angioplasty is due to preconditioning when the size of the area at risk and the collateral flow are taken into account. METHODS AND RESULTS: Thirty-six patients underwent percutaneous transluminal coronary angioplasty. Intracoronary ST segment changes were measured throughout the procedure and used as an endpoint. The size of the area at risk and the collateral perfusion within the ischaemic bed were measured using single photon emission computerized tomography (SPECT). Mean ST segment shift observed in all patients significantly decreased from 11.0+/-2.6 mm during the first balloon inflation to 8.5+/-2.3 mm during the second inflation. This protective effect occurred in the absence of any change in the size of the area at risk (mean: 46+/-5% of LV) and of the collateral perfusion to the ischaemic zone (mean: 23+/-4% of flow in the non-ischaemic zone). CONCLUSION: These results suggest that ischaemic preconditioning does occur during repeated brief coronary artery occlusion in the human heart.

Adolescent↗
PubMed2004

[Coronary pressure measurement for functional evaluation and treatment of intermediate angiographic stenosis].

Accurate understanding of the physiopathology of a coronary stenosis is a major objective in management during diagnostic coronary angiography. Measurement of fractional flow reserve (FFR) by coronary pressure measurement is a reliable method for evaluating the functional consequences of a lesion of the myocardium. This retrospective monocentric study of 114 patients showed that routine coronary pressure measurement for assessing the functional consequences of intermediate (30 to 70% stenosis) lesions or those of ambiguous topography: was necessary in 4% of diagnostic coronary angiographies enabling an immediate management decision. Using this method, 34% of complementary investigations were not performed (stress test, myocardial scintigraphy, dobutamine stress echocardiography). Seventeen per cent of unnecessary angioplasties were also avoided so that acute coronary event were also avoided when lesions with a FFR >0.75 were not treated by angioplasty. A 10-14% reduction in cost was achieved compared with a strategy of systematic angioplasty in respectively mono- or multivessel disease patients and 39% compared with performing ambulatory myocardial scintigraphy in patients with multivessel disease.

Adult↗
PubMed2003

Mechanism of lumen enlargement with direct stenting versus predilatation stenting: influence of remodelling and plaque characteristics assessed by volumetric intracoronary ultrasound.

OBJECTIVE: To compare the effects of arterial remodelling and plaque characteristics on the mechanisms of direct stenting and predilatation stenting. Direct stenting has become routine in some laboratories and differs technically from predilatation stenting. METHODS: Pre- and post-interventional volumetric intravascular ultrasound (IVUS) was undertaken in 30 patients with direct stenting and in 30 with predilatation stenting of non-calcified native coronary lesions, using the same stent design and stent length. Lumen, vessel (external elastic membrane (EEM)), and plaque (plaque + media) volumes were calculated. Remodelling was determined by comparing the EEM area at the centre of the lesion with the EEM areas at proximal and distal reference sites. Plaque eccentricity was defined as the thinnest plaque diameter to the thickest plaque diameter ratio. Plaque composition was characterised as soft, mixed, or dense. RESULTS: All volumetric IVUS changes were similar in the two groups. Pre-intervention remodelling remained uninfluenced after direct stenting, but was neutralised after predilatation stenting. Eccentric lesions responded to intervention by a greater luminal gain owing to greater vessel expansion in direct stenting. Plaque composition influenced luminal gain in direct stenting, the gain being greatest in the softest plaques; in predilatation stenting, luminal gain was equivalent but vessel expansion was greater for "dense" plaque and plaque reduction greater for "soft" plaque. CONCLUSIONS: In non-calcified lesions, the mechanisms of lumen enlargement after direct or predilatation stenting are significantly influenced by atherosclerotic remodelling, plaque eccentricity, and plaque composition.

Catheterization↗
PubMed2002

Multiple atherosclerotic plaque rupture in acute coronary syndrome: a three-vessel intravascular ultrasound study.

BACKGROUND: To test the hypothesis of general atherosclerotic plaque destabilization during acute coronary syndrome (ACS), the present study sought to analyze the 3 coronary arteries by systematic intravascular ultrasound scan (IVUS). METHODS AND RESULTS: Seventy-two arteries were explored in 24 patients referred for percutaneous coronary intervention after a first ACS with troponin I elevation. Fifty plaque ruptures (mean, 2.08 per patient; range, 0 to 6) were diagnosed by the association of a ruptured capsule with intraplaque cavity. Plaque rupture on the culprit lesion was found in 9 patients (37.5%). At least 1 plaque rupture was found somewhere other than on the culprit lesion in 19 patients (79%). These lesions were in a different artery than the culprit artery in 70.8% and were in both other arteries in 12.5% of these 24 patients. Complete IVUS examination of all 3 coronary axes in patients who had experienced a first ACS revealed that multiple atherosclerotic plaque ruptures were detected by IVUS; these multiple ruptures were present simultaneously with the culprit lesion; they were frequent and located (in three quarters of cases) on the 3 principal coronary trunks; and the multiple plaque ruptures in locations other than on the culprit lesion were less severe, nonstenosing, and less calcified. CONCLUSION: Although one single lesion is clinically active at the time of ACS, the syndrome seems nevertheless associated with overall coronary instability.

Acute Disease↗
PubMed2002

[Multiple ruptures of atherosclerotic plaques in acute coronary syndrome. Endocoronary ultrasonography study of three arteries].

The aim of this study was to assess the three coronary arteries systematically by endocoronary ultrasonography in patients with unstable angina to check the hypothesis of global destabilisation of atherosclerotic plaques in acute coronary syndromes (ACS). Sixty two coronary arteries were examined (2.6 per patient). Fifty plaque ruptures were diagnosed (2.08 per patient). Rupture of a plaque of the culprit lesion of the ACS was clearly detected in 9 patients (37.5%). At least one ruptured plaque on a site other than the culprit lesion was observed in 19 patients (79%), on another artery in 70.8% of cases and on two other arteries in 12.5% of cases. A complete endocoronary ultrasonic examination of the three coronary arteries in patients with a first ACS demonstrated that: multiple atherosclerotic plaque rupture may be detected by endocoronary ultrasonography; these multiple plaque ruptures occur simultaneously with the culprit lesion; they are frequent and can be situated on the three main coronary vessels and multiple plaque rupture other than the culprit lesion are less severe, non stenotic and less calcified. Thus, although a single lesion is clinically symptomatic, ACS seems to be associated with global coronary instability.

Acute Disease↗
PubMed2002

[The vulnerable plaque: a necessary concept in the management of atherothrombosis].

The advance of cardiology has improved the prognosis of atherothrombosis through direct diagnosis and early management, but the global incidence of atherothrombotic events has been modified only slightly. Currently, although the stenosing effect of atherosclerosis is well known and if treated hardly poses a problem, the unpredictable risk of arterial thrombosis continues to cause the seriousness of the disease in as much as it is not linked to the degree of stenosis. The initiation of thrombosis progresses via destabilisation phenomena of atherosclerotic plaques with rupture or erosion of the capsule. The identification of plaques "at risk" of instability, so-called "vulnerable" plaques, is thus now a fundamental concept. Thanks to anatomo-pathology, certain morphological and functional criteria of these vulnerable plaques are better understood and are starting to find a clinical resonance. An inflammatory syndrome scenario, thin capsule, and a large lipidic heart associated with an as yet quiescent atherosclerotic plaque are predictive elements of acute coronary syndrome. These elements show promise and an already combined biological and morphological approach will certainly be at the heart of clinical research for years to come.

Arteriosclerosis↗
PubMed2001

Mechanical properties of coronary stents determined by using finite element analysis.

The mechanical function of a stent deployed in a damaged artery is to provide a metallic tubular mesh structure. The purpose of this study was to determine the exact mechanical characteristics of stents. In order to achieve this, we have used finite-element analysis to model two different type of stents: tubular stents (TS) and coil stents (CS). The two stents chosen for this modeling present the most extreme mechanical characteristics of the respective types. Seven mechanical properties were studied by mathematical modeling with determination of: (1) stent deployment pressure, (2) the intrinsic elastic recoil of the material used, (3) the resistance of the stent to external compressive forces, (4) the stent foreshortening, (5) the stent coverage area, (6) the stent flexibility, and (7) the stress maps. The pressure required for deployment of CS was significantly lower than that required for TS, over 2.8 times greater pressure was required for the tubular model. The elastic recoil of TS is higher than CS (5.4% and 2.6%, respectively). TS could be deformed by 10% at compressive pressures of between 0.7 and 1.3 atm whereas CS was only deformed at 0.2 and 0.7 atm. The degree of shortening observed increases with deployment diameter for TS. CS lengthen during deployment. The metal coverage area is two times greater for TS than for CS. The ratio between the stiffness of TS and that of CS varies from 2060 to 2858 depending on the direction in which the force is applied. TS are very rigid and CS are significantly more flexible. Stress mapping shows stress to be localized at link nodes. This series of finite-element analyses illustrates and quantifies the main mechanical characteristics of two different commonly used stents. In interventional cardiology, we need to understand their mechanisms of implantation and action.

Angioplasty↗
PubMed2001

Axial strain imaging of intravascular data: results on polyvinyl alcohol cryogel phantoms and carotid artery.

Mapping the local elastic properties of an atherosclerotic artery is of major interest for predicting the disease evolution or an intervention outcome. These properties can be investigated by elastography, which estimates the strain distribution within a medium in response to a stress. But because diseased arteries are highly heterogeneous, a small global deformation may result in high local strains in the softest regions. For those reasons, we use in this paper the strain estimation method we recently developed to compute elastograms of original vessel-mimicking cryogel phantoms and a fresh excised human carotid artery. This adaptive method has been effectively proved to be accurate in a wider range of strains (0-7%) than commonly used gradient-based methods, and very adapted for investigating highly heterogeneous tissues. Resulting elastograms cover a wider range of strains (0-3.5%) than all previously reported intravascular elastograms, improving the discrimination between healthy and diseased regions.

Carotid Artery Diseases↗
PubMed2001

Modeling the 3D coronary tree for labeling purposes.

Coronary artery diseases are usually revealed using X-ray angiographies. Such images are complex to analyze because they provide a 2D projection of a 3D object. Medical diagnosis suffers from inter- and intra-clinician variability. Therefore, reliable software for the 3D reconstruction and labeling of the coronary tree is strongly desired. It requires the matching of the vessels in the different available angiograms, and an approach which identifies the arteries by their anatomical names is a way to solve this difficult problem. This paper focuses on the automatic labeling of the left coronary tree in X-ray angiography. Our approach is based on a 3D topological model, built from the 3D anthropomorphic phantom, Coronix. The phantom is projected under different angles of view to provide a data base of 2D topological models. On the other hand, the vessel skeleton is extracted from the patient's angiogram. The algorithm compares the skeleton with the 2D topological model which has the most similar vascular net shape. The method performs in a hierarchical manner, first labeling the main artery, then the sub-branches. It handles inter-individual anatomical variations, segmentation errors and image ambiguities. We tested the method on standard angiograms of Coronix and on clinical examinations of nine patients. We demonstrated successful scores of 90% correct labeling for the main arteries and 60% for the sub-branches. The method appears to be particularly efficient for the arteries in focus. It is therefore a very promising tool for the automatic 3D reconstruction of the coronary tree from monoplane temporal angiographic clinical sequences.

Algorithms↗